Influence of the coordination water on the after effects of the K-capture in57Co doped FeSO4×H2O (x=0,1,4,7)

Emission Mössbauer spectroscopy is used to investigate the physico-chemical state of⁵⁷Fe atoms generated by⁵⁷Co²⁺ clectron capture in⁵⁷Co: FeSO₄xH₂O (x=0,1,4,7). The spectra of all the hydrates show at least three main components, the normal bivalent state, Fe²⁺(N), an aliovalent state, Fe³⁺, and one (or several) anomalous ferrous species in which the coordination sphere has been perturbated by the self-radiolysis. No Fe³⁺ is observed in the anhydrous compound whereas the intensity of this component increases as a function of the hydration number, reaching a saturation value of 36% for x=4 and 7.